 Unbolt the exhaust system...  Unbolt the exhaust system from the cats and remove it from the car. This is as simple as removing four 13mm bolts and a few rubber hangers. |
 Using a 19mm ratchet and 19mm...  Using a 19mm ratchet and 19mm wrench, unbolt the driveshaft from the rear yoke. |
 With a 13mm ratchet or wrench,...  With a 13mm ratchet or wrench, remove the bolts that hold the center support of the stock two-piece driveshaft. |
 Slide the driveshaft out from...  Slide the driveshaft out from the transmission and set it aside. Note the rubber "donuts" that attach the yokes. This is a big area for improvement that we'll address in future issues. |
Follow along as we upgrade the clutch and shifter in our late-model Goat for more clamping power and a better overall shift quality.
Special thanks to Jon Schwenn, Ryan Bowman, and Shawn Sullivan.
On The Road And On The Dyno
With the clutch installed, it was time to endure a long, 500-mile no-WOT or hard-launch break-in period. It's also important to try and avoid slipping the clutch any more than necessary. The pedal feel is definitely considerably firmer, and the clutch did chatter quite a bit at the beginning of the break-in. While breaking in the clutch, we finally got to experience the GMM RipShift firsthand after hearing people rave about it. The RipShift is incredibly precise and feels as though you are shifting with a hammer-it's confidence inspiring. In addition, through the use of some relatively heavy centering springs, the shifter lines itself up for a 2-3 and 3-4 shift; all you have to do is push or pull.
After we had completed the requisite 500 miles, the clutch chatter was considerably reduced, and the pedal got a slight bit softer but was still quite firm. While it's a driveable clutch, it could get quite heavy in stop-and-go traffic; it's really a personal preference here.
For a lighter pedal feel, S.P.E.C. now offers a new Stage 3+ that holds 700 lb-ft torque with a full-faced disc but drives like a Stage 2+. The regular Stage 2 will hold the power the GTO makes right now, but we are preparing for the future.
While we did expect to see a slight power increase due to the lower rotating mass of the S.P.E.C. Stage 3 assembly, the results were actually quite impressive.
On Vector Motorsports Mustang chassis dyno, our GTO put down a solid 452.7 hp. What's significant, however, is that in its previous pull prior to the clutch, it put down only 444.5 hp. We freed up over 8 hp by switching to the lighter, more durable S.P.E.C. Stage 3 clutch. Torque remained mostly unchanged from 393 ft-lb to just over 394. All testing was done in 85-90-degree ambient temperatures with intake air temps well over 100 degrees-not exactly conditions that will make a supercharged car shine. So not only did we get the added benefit of a clutch that can handle considerably more power, but also one that actually freed up more of it.